The present invention relates to the field of x-ray inspection systems, and in particular to an x-ray inspection for inspecting personnel.
The x-ray systems currently used to inspect people are based on using a scanning pencil beam of x-rays to produce an x-ray backscatter image. The pencil beam is formed by two collimators. The first collimator is a fixed slit and the second collimator is a rotating slit. As the rotating slit passes across the fixed slit, a single line of data is formed. For example, see U.S. Pat. No. 3,780,291 entitled xe2x80x9cRadiant Energy Imaging With Scanning Pencil Beamxe2x80x9d by Stein et al. Subsequent lines of data are produced by translating the entire pencil beam forming apparatus across the body of the person under inspection. These systems typically operate at 70-140 KV peak.
A problem with these systems is that they are rather large, and require an x-ray source that includes a rotating collimator.
Therefore, there is a need for an improved personnel x-ray inspection, including a personnel x-ray inspection system that includes an x-ray source which provides a collimated traveling pencil beam of x-rays without the need for a moving (e.g., rotating) collimator assembly.
Briefly, according to an aspect of the present invention, a personnel x-ray inspection system includes an electron source that provides a pencil beam of electrons. An electromagnet assembly receives the pencil beam of electrons and directs the beam of electrons along a straight line under the control of a scan command signal to form a scanning redirected beam. The scanning redirected beam strikes a target and generates a cone of x-rays that moves along a straight target line as a result of the scanning redirected beam. A collimator receives the scanning cone of x-rays and generates a collimated traveling pencil beam, which is directed to a person under inspection. A moving platform translates the person under inspection relative to the collimated traveling pencil beam. A backscatter detector detects backscattered x-rays, and provides a backscattered detected signal indicative thereof. A system controller provides the scan command signal, and also receives and processes the backscattered detected signal to provide an image signal indicative of the person under inspection.
In a first embodiment, the personnel x-ray inspection system includes a rotating base on which the person under inspection stands to rotate the person under inspection relative to the collimated traveling pencil beam of x-rays. In a second embodiment, the system includes a moving platform on which the person under inspection stands to translate the person under inspection longitudinally relative to the collimated traveling pencil beam of x-rays. In this second embodiment, the person is then turned around and translated again through the collimated traveling pencil beam of x-rays.
Advantageously, the personnel x-ray inspection system uses a scanning pencil beam, and produces a line of data without requiring any moving parts. In addition, subsequent lines of data are produced without moving the collimator.
The pencil beam preferably moves repetitively in a straight line that does not translate as the image is formed. The translation is produced by the motion of the person being inspected. This feature allows the use of a relatively narrow beam catcher for the x-rays. The beam catcher is mounted behind the person and may be a few inches wide by about six feet long.